SANSUI 9090DB NO AM/FM

[nicolas25]

Hello everyone, i have a Sansui 9090db being stucked for years.when i tried to use this morning, all working fine except no AM and FM signal.any idea where to start? thanks

 

[DougBrewster]

Check the tuner power supply F2619 for 12.5V output. These power supplies run very hot and fail as a result.

 

[nicolas25]

Check the tuner power supply F2619 for 12.5V output. These power supplies run very hot and fail as a result.

thanks, later i will measure the output. i took a quick look at the board 2619 and 1 cap seems bulging, its a 100uf 35v (blue cap)

 

[Robisme]

Also check the solder connections on the big white resistors. They are known to fail.

Are you aware of the procedure to remove the tuner section? It helps in servicing the 9090DB.

Rob

 

[Blue Shadow]

I had to change the big resistors to drop enough voltage to not burn up the caps which were replaced, too. That whole board had piles of overheated/overvoltaged parts.

 

[nicolas25]

Also check the solder connections on the big white resistors. They are known to fail.

Are you aware of the procedure to remove the tuner section? It helps in servicing the 9090DB.

Rob

i will check maybe tomorrow, thanks

 

[nicolas25]

I had to change the big resistors to drop enough voltage to not burn up the caps which were replaced, too. That whole board had piles of overheated/overvoltaged parts.

you mean the white resistors?

 

[AlTinkster92]

Try cleaning the selector switch? Sometimes its the easy things....

 

[Blue Shadow]

you mean the white resistors?

yes. Measure voltage out of it and it should be kinda within the specs of the cap voltage. I had like 50 or something and the caps were 35 or whatever, no wonder stuff looked burned up.

 

[nicolas25]

Try cleaning the selector switch? Sometimes its the easy things....

ok thanks

 

[Robisme]

Don't test that supply without a load on it. The voltage will be high and a cap will blow. Been there done that.

Rob

 

[nicolas25]

Don't test that supply without a load on it. The voltage will be high and a cap will blow. Been there done that.

Rob

im sorry i cant get what you mean. sorry for my poor english and comprehension, im from spain.

 

[nicolas25]

by the way, i checked the white resistors in circuit and their resistance is about 150 ohms each. i remove them from the board and they measure at 270 ohms each. i replaced the bulging cap, 100uf 35 v, i tried to power on then the 100uf cap burned again

 

[LBPete]

There is nothing obviously wrong with the caps in this photo and the board does not appear to have been overheated.

The white resistors should be 270 ohms each. They are wired in series giving the pair a total of 540 ohms.

What is the voltage output from pin 01? Measure between that pin and the metal chassis. If you have no voltage output, check the solder joints on those white resistors,

- Pete

 

[Robisme]

Some schematics show they are 270 and some show 330 ohm. They are in parallel so 150 ohm is about right.

don’t power up the receiver if that power supply is not connected. It will blow a cap.

Rob

 

[nicolas25]

a quick update, i checked the components of the board 2619 and TR02 which is C1211 transistor is open. i replaced it with BC639 and replaced the 100uf 35v cap and voila, its now working.thanks for the help guys!

 

[LBPete]

The white resistors should be 270 ohms each. They are wired in series giving the pair a total of 540 ohms.

Sorry, my memory is not as good as it used to be. They are indeed in parallel providing a 135 ohm load.

- Pete

 

[Buddy69]

Also check the solder connections on the big white resistors. They are known to fail.

Are you aware of the procedure to remove the tuner section? It helps in servicing the 9090DB.

Rob

Good day sir. I am also having problems with the Sansui 9090 DB tuner. I have found two bad transistors on the 2619 board. The d313 and the c1211. I am finding 50 to 60 volts on this board. Does that sound normal to you. If not do you know where I should look to find the culprit. Thank you for any open good day.

 

[Tom B]

46 volts comes in at point "J" (pin 3) feeding the 270 ohm resistors that are in parallel. you should then wind up with about 14v on the collector of that TO220 transistor 2sd313, and 12.5v on the emitter resulting as 12.5 on pin 1 of the board. also need to check the 2sc1384 and the 6 volt zener diode for short or open. resoldering of the 2 large 270 ohm resistor connecting are usually needed as they run very hot.